Re: IO error catching

[Erwin Rol <Erwin Rol q-soft-engineering com>]

Owen Taylor wrote:
> 
> There is no way with Xlib to recover from a IO error. Period.
> 
>        The XSetIOErrorHandler sets the fatal I/O error handler.
>        Xlib calls the program's supplied error handler if any
>        sort of system call error occurs (for example, the connec­
>        tion to the server was lost).  This is assumed to be a
>        fatal condition, and the called routine should not return.
>        If the I/O error handler does return, the client process
>        exits.

Yeah i read that part, and i very much disliked it very much :-/

> 
> Xlib internals would most likely be left in an inconsistent state if
> you long-jumped out. Using two processes as David Helder suggested
> would be the best way to handle things.

Yeah you are problably right, i think it is a rather serious design flaw
(of Xlib
not GTK+ ) though, when a library forces you to exit your programm
because it is 
not able to handle a error in a good way.

It would be very nice when GTK+ had some way to register Error handlers
though,
unless using Xlib functions is recommended practice.

Oh well i will keep trying, cause
for every solution there is a problem :-)

- Erwin


> 
> Regards,
>                                         Owen
> 
> Erwin Rol <Erwin Rol q-soft-engineering com> writes:
> 
> > Hello All,
> >
> > Is there a way to return from the main loop in case of a "fatal"
> > IO error (for example the X-Server died). And after that return
> > being able to (try) reconnect to the X-Server again. I am thinking about
> > and application where there are two computers, one with the programm
> > that
> > always runs, and one with the X-Server that doesn't always runs. Both
> > computers are connected via cross over with known IP numbers. The one
> > with the X-Server has just the X-Server and nothing else as it is turned
> > on it starts the X-Server, nothing else. The programm runnign on the
> > other
> > computer detects the X-Server and connects. When the computer with
> > the X-Server is turned off, the programm on the other computer should
> > not die
> > but keep running and keep retrying to connect to the X-Server.
> >
> > I though somethign like a longjmp from the error handler to the mainloop
> > and
> > exit from the loop. The main problem is probably clean up without
> > getting into
> > a endless error loop, or having memory leaks.
> >
> > Any hints, "you are an idiot" msgs, or quiestions are welcome,
> 
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